The present invention relates to manufacturing of metal eyewear frames. The invention more particularly relates to a fixture which allows for rapid changeovers between different induction brazing units at a single work station.
Metal eyewear frames are manufactured in an ever-changing variety of styles. A common metal eyewear frame includes right and left eyewires wherein right and left lenses are secured. A separate bridge element and/or brace interconnects the eyewires, and a pair of nose pads are typically attached to the front frame adjacent the bridge. A pair of temples are pivotally secured to opposite sides of the front frame to complete the eyewear frame assembly. Common methods employed to join the various metal components of an eyewear frame together include resistance brazing and induction brazing. Induction brazing is more difficult and expensive to carry out than resistance brazing but provides a superior connection between the metal parts.
In induction brazing, the eyewear frame components to be joined are positioned in a work piece holder mounted to a work surface. An induction unit having a base is mounted to the work surface adjacent to the work piece holder (typically behind the work piece holder). Induction units are commercially available through HAUG of Switzerland. The induction unit carries an induction coil which has a configuration matched to the particular eyewear components being joined. The induction unit base is mounted to the work surface with the induction coil extending to the work piece in a very precise positional relationship. A worker places the metal frame parts into the work piece holder and activates the induction coil to join the parts.
As stated, the configuration and placement of the induction coil must be precisely matched to the configuration of the work piece. A single eyewear frame may require induction brazing of many parts, e.g., the nose pad arms to the eyewires, the eyewires to the bridge and/or brace, and end pieces to the opposite side of the eyewires. Prior to the present invention, either multiple induction brazing work stations were required to join these different joints, each with its own specially configured and positioned induction coil, or the induction units themselves would need to be changed at a particular work station. Both of these options have proven expensive. Each induction work station costs upwards of $40,000.00USD and it is therefore an expensive proposition to have a separate work station for each joint being brazed for every style of eyewear frame being produced. Furthermore, to change induction units at a single work station is also very expensive in that it typically requires two to three days to complete a changeover of induction units due to the exacting configuration and positioning requirements of the induction coils with regard to the particular work piece. Quickly identifying the proper coil configuration for a particular frame style and joint is also a problem. Thus, while induction brazing of metal eyewear frames is very desirable from the standpoint of quality, it is also very expensive and problematic for the reasons discussed above.